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A Corps area was a geographically-based organizational structure (
military district Military districts (also called military regions) are formations of a state's armed forces (often of the Army) which are responsible for a certain area of territory. They are often more responsible for administrative than operational matters, and ...
) of the
United States Army The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, ...
used to accomplish administrative, training and tactical tasks from 1920 to 1942. Each corps area included divisions of the
Regular Army A regular army is the official army of a state or country (the official armed forces), contrasting with irregular forces, such as volunteer irregular militias, private armies, mercenaries, etc. A regular army usually has the following: * a standi ...
,
Organized Reserve The United States Army Reserve (USAR) is a reserve force of the United States Army. Together, the Army Reserve and the Army National Guard constitute the Army element of the reserve components of the United States Armed Forces. Since July 2020, ...
and
National Guard of the United States The National Guard is a state-based military force that becomes part of the reserve components of the United States Army and the United States Air Force when activated for federal missions.mobilization Mobilization is the act of assembling and readying military troops and supplies for war. The word ''mobilization'' was first used in a military context in the 1850s to describe the preparation of the Prussian Army. Mobilization theories and t ...
problems during World War I, this organization provided a framework to rapidly expand the Army in time of war or national emergency such as the
Great Depression The Great Depression (19291939) was an economic shock that impacted most countries across the world. It was a period of economic depression that became evident after a major fall in stock prices in the United States. The economic contagion ...
. The nine corps areas, created by the War Plans Division under authority of
United States War Department The United States Department of War, also called the War Department (and occasionally War Office in the early years), was the United States Cabinet department originally responsible for the operation and maintenance of the United States Army, a ...
General Order No. 50 on 20 August 1920, had identical responsibilities for providing peacetime administrative and logistical support to the army's mobile units as was provided by the six territorial "
Department Department may refer to: * Departmentalization, division of a larger organization into parts with specific responsibility Government and military *Department (administrative division), a geographical and administrative division within a country, ...
s" they replaced. In addition, the corps areas took on the responsibilities for post and installation support units (" Zone of the Interior" units) created during World War I. Corps areas had the added responsibility for planning and implementing mobilization plans for all Regular Army, National Guard, and Organized Reserve mobile units in their respective geographic areas; the development and administration of hundreds of new Organized Reserve and
Reserve Officers Training Corps The Reserve Officers' Training Corps (ROTC ( or )) is a group of college- and university-based officer-training programs for training commissioned officers of the United States Armed Forces. Overview While ROTC graduate officers serve in all ...
(ROTC) units; and managing the personnel records for thousands of Reserve officers, enlisted personnel, ROTC cadets, and
Citizens Military Training Camp Citizens' Military Training Camps (CMTC) were military training programs of the United States. Held annually each summer during the years 1921 to 1940, the CMTC camps differed from National Guard and Organized Reserve training in that the program ...
(CMTC) candidates. The composition of the corps areas divided the United States geographically by state lines and population density into nine multi-state area commands roughly equal in population. Each corps area was responsible for organizing two tactical corps consisting of three infantry divisions each. Each corps area also had responsibility for organizing various other
field army A field army (or numbered army or simply army) is a military formation in many armed forces, composed of two or more corps and may be subordinate to an army group. Likewise, air armies are equivalent formation within some air forces, and with ...
, General Headquarters Reserve, Zone of the Interior (later designated as Corps Area Service Command), and
Communications Zone {{Short description, Aspect of military theater of war operations Communications Zone is a US Army and NATO term which describes a part of the theater of war operations. The Communications Zone is the rear part of theater of operations (behind but ...
units. The First, Second, Third, Fourth, Eighth, and Ninth Corps Areas also organized units to man various fixed coastal defenses. The corps areas were further grouped into three army areas of two field armies each.


Early army administrative units

For the century preceding 1920 the U.S. Army was geographically divided into series of Military Divisions, "Departments" and smaller "
Districts A district is a type of administrative division that, in some countries, is managed by the local government. Across the world, areas known as "districts" vary greatly in size, spanning regions or counties, several municipalities, subdivisions o ...
" and Subdistricts. Departments and divisions were numbered or named for their geographic location. Before the
War of 1812 The War of 1812 (18 June 1812 – 17 February 1815) was fought by the United States, United States of America and its Indigenous peoples of the Americas, indigenous allies against the United Kingdom of Great Britain and Ireland, United Kingdom ...
these administrative units were geographically named starting with the Department of the East and Department of the West. About 1815, the areas were numbered until after the Civil War. After the Civil War, the system used until after World War I was again geographically identified; i.e. Department of the East or Department of the Missouri and subordinate units were called divisions or districts. The last reorganization of departments was done in 1917 after the beginning of World War I.


National Defense Act of 1920 and establishment of corps area-level organizations

Authorized by the National Defense Act of 1920, which amended the
National Defense Act of 1916 The National Defense Act of 1916, , was a United States federal law that updated the Militia Act of 1903, which related to the organization of the military, particularly the National Guard. The principal change of the act was to supersede provi ...
, nine multi-state sized "corps areas" were established on 20 August 1920 by the U.S. Army Chief of Staff through War Department General Order Number 50. The corps areas were formed for administration, training, and tactical control of the army, replacing the six geographical (or territorial) military departments into which the continental United States had been divided since 1917 and with little variation since the Civil War. Three overseas commands: the
Hawaiian Department Hawaiian may refer to: * Native Hawaiians, the current term for the indigenous people of the Hawaiian Islands or their descendants * Hawaii state residents, regardless of ancestry (only used outside of Hawaii) * Hawaiian language Historic uses * ...
,
Panama Canal Department The Panama Canal Department was a department (geographical command) of the United States Army, responsible for the defense of the Panama Canal Zone between 1917 and 1947. First U.S. Army presence The Isthmian Canal Commission and the Panama Ca ...
, and the
Philippine Department The Philippine Department (Filipino: ''Kagawaran ng Pilipinas/Hukbong Kagawaran ng Pilipinas'') was a regular United States Army organization whose mission was to defend the Philippine Islands and train the Philippine Army. On 9 April 1942, durin ...
continued to be identified as departments. The 1920 act was a realization that the mobilization of a citizen army could no longer meet the defense needs of the United States and for the first time placed an emphasis on peacetime preparedness. Yet with its passage, Congress never fully funded the program. But Congress did recognize the value of a professional officer education program by enhancing existing general service schools such as the
Command and General Staff School The United States Army Command and General Staff College (CGSC or, obsolete, USACGSC) at Fort Leavenworth, Kansas, is a graduate school for United States Army and sister service officers, interagency representatives, and international military ...
at
Fort Leavenworth Fort Leavenworth () is a United States Army installation located in Leavenworth County, Kansas, in the city of Leavenworth. Built in 1827, it is the second oldest active United States Army post west of Washington, D.C., and the oldest perma ...
, Kansas, and the Army War College at
Carlisle Barracks Carlisle Barracks is a United States Army facility located in Carlisle, Pennsylvania. The site of the U.S. Army War College, it is the nation's second-oldest active military base. The first structures were built in 1757, during the French and I ...
, Pennsylvania. The act authorized the establishing new schools to meet modern military educational needs, such as the
Army Industrial College The Dwight D. Eisenhower School for National Security and Resource Strategy (Eisenhower School), formerly known as the Industrial College of the Armed Forces (ICAF), is a part of the National Defense University. It was renamed on September 6, 20 ...
in 1924. Thirty-one additional special service schools were established or improved to provide training to the various branches of the Army. The act established the
division Division or divider may refer to: Mathematics *Division (mathematics), the inverse of multiplication *Division algorithm, a method for computing the result of mathematical division Military *Division (military), a formation typically consisting ...
as a basic Army unit, replacing the pre-World War I notion of the regiment in war planning. Tactically and administratively, each corps area commander was the senior army officer for his geographical area, typically functioning as a commanding general of an existing Regular Army corps or division in their area. During times of
civil unrest Civil disorder, also known as civil disturbance, civil unrest, or social unrest is a situation arising from a mass act of civil disobedience (such as a demonstration, riot, strike, or unlawful assembly) in which law enforcement has difficulty m ...
, labor strikes, or
natural disaster A natural disaster is "the negative impact following an actual occurrence of natural hazard in the event that it significantly harms a community". A natural disaster can cause loss of life or damage property, and typically leaves some econ ...
s, corps area commanders provided Army resources needed to address the emergency. Each corps area was allocated two "type" corps (with a standard table of organization) and six infantry divisions. The corps were numbered in accord with their corps area designation, i.e. I and XI Corps in the First Corps Area. The lower numbered corps (I through IX) consisted of one Regular Army and two
National Guard National Guard is the name used by a wide variety of current and historical uniformed organizations in different countries. The original National Guard was formed during the French Revolution around a cadre of defectors from the French Guards. N ...
divisions among the various states of the corps area. The higher numbered corps (XI through XIX) each consisted of three divisions, also assigned by state boundaries, of the newly established (but rarely funded)
Organized Reserve The United States Army Reserve (USAR) is a reserve force of the United States Army. Together, the Army Reserve and the Army National Guard constitute the Army element of the reserve components of the United States Armed Forces. Since July 2020, ...
. By 1925, in the face of steady Coolidge Administration and congressional budget cutting, the United States Army only had three active regular divisions nationwide; the remainder of its divisions, both regular and reserve components, only existed on paper. The amended National Defense Act also grouped three corps areas into an "army level" mobilization organization whose boundaries were also identical for the two "type"
armies An army (from Old French ''armee'', itself derived from the Latin verb ''armāre'', meaning "to arm", and related to the Latin noun ''arma'', meaning "arms" or "weapons"), ground force or land force is a fighting force that fights primarily on ...
located within them. For example, First, Second, and Third Corps Areas, and the First and Fourth (Field) Armies, comprised the First "Army Area". The 1921 mobilization planning that created the six field army headquarters did not envision a need for active field army-level commands in peacetime and thus the headquarters were constituted in the Organized Reserve rather than the Regular Army. Until fully activated with its own headquarters staff, an army area was typically jointly staffed, headquartered, and commanded by the most senior corps commander in that area. Between 1927 and 1933 all six field army headquarters were deactivated as the Army wrestled with structure, mobilization, and manpower issues.


Corps area and army area organizations, 1921-1932

An army area included three corps areas, and in the early years was concurrently staffed and headquartered with one of the corps areas. For example, First Army Area headquarters staff was also the Second Corps Area headquarters staff based at
Fort Jay Fort Jay is a coastal bastion fort and the name of a former United States Army post on Governors Island in New York Harbor, within New York City. Fort Jay is the oldest existing defensive structure on the island, and was named for John Jay, a mem ...
at
Governors Island Governors Island is a island in New York Harbor, within the New York City borough of Manhattan. It is located approximately south of Manhattan Island, and is separated from Brooklyn to the east by the Buttermilk Channel. The National Park S ...
in New York, New York; Sixth Corps Area provided the Second Army Area headquarters staff.


First Army Area

First Army Area included First Army (Active) and Fourth Army (reserve on paper). * First Corps Area replaced the Northeastern Department, and was headquartered in Boston Army Base, Massachusetts, encompassing Maine, Massachusetts, New Hampshire, Rhode Island, Vermont and Connecticut. It was responsible for the mobilization, and administration of the
First United States Army First Army is the oldest and longest-established field army of the United States Army. It served as a theater army, having seen service in both World War I and World War II, and supplied the US army with soldiers and equipment during the Kor ...
(1936–38); the Fourth Army, I Army Corps with 9th Division, 26th Division, 43d Division; XI Corps with three divisions; coast defense units of the First Coast Artillery District, some units of the GHQ Reserve, and the Zone of the Interior support units of the First Corps Area Service Command. First Corps Area was redesignated First CASC in May 1941. *Second Corps Area replaced the Eastern Department, headquartered at
Fort Jay Fort Jay is a coastal bastion fort and the name of a former United States Army post on Governors Island in New York Harbor, within New York City. Fort Jay is the oldest existing defensive structure on the island, and was named for John Jay, a mem ...
on
Governors Island Governors Island is a island in New York Harbor, within the New York City borough of Manhattan. It is located approximately south of Manhattan Island, and is separated from Brooklyn to the east by the Buttermilk Channel. The National Park S ...
in New York City and encompassed New York, New Jersey, Delaware and from 1921 to 1937, the District of Puerto Rico. *Formations included the
United States First Army First Army is the oldest and longest-established field army of the United States Army. It served as a theater army, having seen service in both World War I and World War II, and supplied the US army with soldiers and equipment during the Kor ...
(1921–36 and 1938–41); Fourth Army (1921–33); the
II Corps (United States) The II Corps was a corps-sized formation of the United States Army that was active in both World War I and World War II. It was originally formed and fought on the Western Front during World War I and was also the first American formation ...
, with the 1st Infantry Division, the only active division in the area; the 27th Infantry Division of the New York National Guard; and the 44th Infantry Division of the New Jersey, New York, and Delaware National Guards; and
XII Corps (United States) The XII Corps fought from northern France to Austria in World War II. Constituted in the Organized Reserves in 1933, it was activated on 29 August 1942 at Columbia, South Carolina. XII Corps became operational in France as part of Lieutenant G ...
, assigned the 77th Division, 78th Division, and 98th Division of the
Organized Reserves The United States Army Reserve (USAR) is a reserve force of the United States Army. Together, the Army Reserve and the Army National Guard constitute the Army element of the reserve components of the United States Armed Forces. Since July 2020, ...
. Also in the corps area was the
21st Cavalry Division (United States) The 21st Cavalry Division was a division of the United States Army National Guard located in the north eastern United States. The division was composed of personnel from the New York, New Jersey, Pennsylvania and Rhode Island Army National Guard ...
of the New York, Pennsylvania, Rhode Island, and New Jersey National Guards; the 61st Cavalry Division of the Organized Reserves; the Second Coast Artillery District; and the Second Corps Area Service Command. *Third Corps Area variously headquartered at
Fort McHenry Fort McHenry is a historical American coastal pentagonal bastion fort on Locust Point, now a neighborhood of Baltimore, Maryland. It is best known for its role in the War of 1812, when it successfully defended Baltimore Harbor from an attack ...
and Fort Howard in Baltimore, Maryland and included Pennsylvania, Maryland, District of Columbia and Virginia. Responsible for units of the First and Fourth Armies, III Army Corps (
8th 8 (eight) is the natural number following 7 and preceding 9. In mathematics 8 is: * a composite number, its proper divisors being , , and . It is twice 4 or four times 2. * a power of two, being 2 (two cubed), and is the first number of ...
, 28, 29 Divisions) and XIII Army Corps ( 79th, 80th, 99th Divisions, coast defense units of the Third Coast Artillery District, select units of the GHQ Reserve, and the Z.I. support units of the Third CASC. From 15 October 1921, included the 62nd Cavalry Division, Organized Reserves (also part of Fourth Army); included the 2d Observation Wing, later 2d Wing, from 20 August 1920. From 1921 to 30 September 1927,
Washington D.C. ) , image_skyline = , image_caption = Clockwise from top left: the Washington Monument and Lincoln Memorial on the National Mall, United States Capitol, Logan Circle, Jefferson Memorial, White House, Adams Morgan, N ...
was withdrawn from the Third Corps Area and established as the District of Washington. After discontinuation, DC duties were taken on by the 16th Infantry Brigade. The 14th Aero Squadron (or 14th Bombardment Squadron) was assigned to the Third Corps Area, August 28, 1933 and then transferred to the
9th Bombardment Group 9 (nine) is the natural number following and preceding . Evolution of the Arabic digit In the beginning, various Indians wrote a digit 9 similar in shape to the modern closing question mark without the bottom dot. The Kshatrapa, Andhra an ...
, on March 1, 1935. HQ Third Corps Area was redesignated Third CASC in May 1941.


Second Army Area

Second Army Area included Second Army (Active) and Fifth Army (reserve on paper). * Fourth Corps Area replaced the Southeastern Department based in Charleston, South Carolina and was originally headquartered there then transferred to Atlanta, Georgia, and encompassed the states of Alabama (for a period), Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina and Tennessee. Formations included Third Army (1936–40); IV Corps: 4th Division, 30th Division, 31st Division; XIV Corps: 81st Division, 82d Division, 87th Division; Fourth Coast Artillery District; and Fourth Corps Area Service Command. *
Fifth Corps Area The Fifth Corps Area was a military district of the United States Army from 1920-21 to the Second World War. The Fifth Corps Area included the states of Indiana, Ohio, West Virginia, and Kentucky. Eventually it became Fifth Service Command on 22 Jul ...
was established on 20 August 1920 with headquarters at
Fort Benjamin Harrison Fort Benjamin Harrison was a U.S. Army post located in suburban Lawrence Township, Marion County, Indiana, northeast of Indianapolis, between 1906 and 1991. It is named for the 23rd United States president, Benjamin Harrison. History In 1901, ...
, Indiana, and organized from parts of the discontinued
Central Department Central () is a department in Paraguay. The capital is Areguá. With 2,243,792 inhabitants, it is the most populated and the smallest of the 17 departments of Paraguay. Boundaries *North: the departments of Cordillera and Presidente Hayes *Wes ...
. The headquarters was transferred to
Fort Hayes Fort Hayes is a military post in Columbus, Ohio, United States. Created by an act of the United States Congress on July 11, 1862, the site was also known as the Columbus Arsenal until 1922, when the site was renamed after former Ohio Governor ...
,
Columbus, Ohio Columbus () is the state capital and the most populous city in the U.S. state of Ohio. With a 2020 census population of 905,748, it is the 14th-most populous city in the U.S., the second-most populous city in the Midwest, after Chicago, and ...
, on 20 June 1922. The Fifth Corps Area included the states of Indiana, Ohio, West Virginia, and Kentucky. The headquarters was responsible for the units of the
Second The second (symbol: s) is the unit of time in the International System of Units (SI), historically defined as of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds each ...
and Fifth Armies, the V Army Corps (5th, 37th, and 38th Divisions) and XV Army Corps (83rd, 84th, 100th Infantry Divisions), select GHQ Reserve units, and Zone of the Interior support units of the Fifth Corps Area Support Command. Mobile units of the corps area, less GHQ Reserve and Z.I. units, were assigned to the Second and Fifth Armies from 1921 to 1933. With the adoption of the four field army plan on 1 October 1933, the units of the Fifth Corps Area were reassigned to the Second Army, GHQR, or demobilized. *
Sixth Corps Area Sixth Corps Area was a Corps area, effectively a military district, of the United States Army from 1921 to the 1940s. The headquarters was established at Fort Sheridan, Illinois, in August 1920, from portions of the former Central Department, but t ...
covered the states of Wisconsin, Michigan and Illinois and
Jefferson Barracks The Jefferson Barracks Military Post is located on the Mississippi River at Lemay, Missouri, south of St. Louis. It was an important and active U.S. Army installation from 1826 through 1946. It is the oldest operating U.S. military installation ...
, Missouri. The headquarters was established at Fort Sheridan, Illinois, in August 1920, from portions of the former Central Department, but then moved to the
U.S. Post Office The United States Postal Service (USPS), also known as the Post Office, U.S. Mail, or Postal Service, is an Independent agencies of the United States government, independent agency of the executive branch of the Federal government of the Uni ...
Building at 1819 West Pershing Road in Chicago on 10 October 1921. Sixth Corps Area was responsible for the mobilization, administration, and training of units of the Second and Fifth Armies, I Cavalry Corps (Regular Army, but inactive, 1927–1940), VI Army Corps (including the Regular Army 6th Division, 32d and 33rd Divisions) and XVI Army Corps (85th, 86th, 101st Divisions), select GHQ Reserve units, and the Zone of the Interior support units of the Sixth Corps Area Support Command.


Third Army Area

Third Army Area included Third Army (Active), including, seemingly, the Reserve
23rd Cavalry Division (United States) The 23rd Cavalry Division was a cavalry formation of the United States Army National Guard during the interwar period. It was created in the early 1920s due to the perceived need for additional cavalry units along with three other National Guar ...
, and Sixth Army (reserve on paper). * Seventh Corps Area initially included Kansas, Minnesota, Missouri (but not Jefferson Barracks), North Dakota, South Dakota, Iowa and Nebraska. Responsibility for Arkansas was transferred from the Fourth Corps Area to the Seventh Corps Area on 1 December 1920. The headquarters was established on 20 August 1920 with headquarters at Fort Crook, Nebraska, again from elements of the previous Central Department. HQ, Seventh Corps Area moved to Fort Omaha, NE, on 27 May 1922 and further moved to the Army Building at 15th and Dodge Streets in Omaha - the Omaha Army Depot - on 25 March 1929. *
Eighth Corps Area A Corps area was a geographically-based organizational structure (military district) of the United States Army used to accomplish administrative, training and tactical tasks from 1920 to 1942. Each corps area included divisions of the Regular Army ...
, variously headquartered in Dallas and
Fort Sam Houston Fort Sam Houston is a U.S. Army post in San Antonio, Texas. "Fort Sam Houston, TX • About Fort Sam Houston" (overview), US Army, 2007, webpageSH-Army. Known colloquially as "Fort Sam," it is named for the U.S. Senator from Texas, U.S. Represen ...
in
San Antonio ("Cradle of Freedom") , image_map = , mapsize = 220px , map_caption = Interactive map of San Antonio , subdivision_type = Country , subdivision_name = United States , subdivision_type1= State , subdivision_name1 = Texas , subdivision_t ...
, Texas, replaced the Southern Department and included Texas, Oklahoma, Colorado, New Mexico and Arizona. The 154th Observation Squadron was assigned to the Eighth Corps Area on 16 September 1940, but was later reassigned to Third Army. *At the end of General Frank M. Andrews' four-year term as Commanding General of
GHQ Air Force The United States Army Air Corps (USAAC) was the aerial warfare service component of the United States Army between 1926 and 1941. After World War I, as early aviation became an increasingly important part of modern warfare, a philosophical ri ...
on March 1, 1939, he was not reappointed, reverted to his permanent rank of colonel, and was reassigned as air officer for the Eighth Corps Area in San Antonio, the same exile to which
Billy Mitchell William Lendrum Mitchell (December 29, 1879 – February 19, 1936) was a United States Army officer who is regarded as the father of the United States Air Force. Mitchell served in France during World War I and, by the conflict's end, command ...
had been sent. Possibly expected to retire, he instead was recalled to Washington just four months later by Marshall after President
Franklin D. Roosevelt Franklin Delano Roosevelt (; ; January 30, 1882April 12, 1945), often referred to by his initials FDR, was an American politician and attorney who served as the 32nd president of the United States from 1933 until his death in 1945. As th ...
named
George C. Marshall George Catlett Marshall Jr. (December 31, 1880 – October 16, 1959) was an American army officer and statesman. He rose through the United States Army to become Chief of Staff of the US Army under Presidents Franklin D. Roosevelt and Harry ...
to serve as
Chief of Staff of the United States Army The chief of staff of the Army (CSA) is a statutory position in the United States Army held by a general officer. As the highest-ranking officer assigned to serve in the Department of the Army, the chief is the principal military advisor and a ...
following
Malin Craig Malin Craig (August 5, 1875 – July 25, 1945) was a general in the United States Army who served as the 14th Chief of Staff of the United States Army from 1935 to 1939. He served in World War I and was recalled to active duty during World War ...
's retirement. *Ninth Corps Area, headquartered at the
Presidio of San Francisco The Presidio of San Francisco (originally, El Presidio Real de San Francisco or The Royal Fortress of Saint Francis) is a park and former U.S. Army post on the northern tip of the San Francisco Peninsula in San Francisco, California, and is part o ...
, California, replaced the Western Department and included Alaska, Idaho, Montana, California, Wyoming, Washington, Utah, Nevada and Oregon. Included the 41st Division, the 18th Squadron (Observation) from October 1921 to July 1922; the 19th Squadron (Pursuit) October 1921-June 1922; and the 7th Bombardment Group from 1 June 1928 - c. 30 October 1931, and then again from c. 1 October 1933 - 1 March 1935. 17th Attack Group was located at
March Field March is the third month of the year in both the Julian and Gregorian calendars. It is the second of seven months to have a length of 31 days. In the Northern Hemisphere, the meteorological beginning of spring occurs on the first day of Mar ...
from 1931 but reported to the
1st Bombardment Wing The 1st Bombardment Wing is a disbanded United States Army Air Force unit. It was initially formed in France in 1918 during World War I as a command and control organization for the Pursuit Groups of the First Army Air Service. Demobilized afte ...
. The 91st Aero Squadron, later the 91st Observation Squadron, was almost continuously associated with the Ninth Corps Area from its reformation on 20 August 1920 until 1940. The 805th Observation Squadron was constituted in the Organized Reserve (Oregon) on 31 March 1924; and was then consolidated on 8 December 1936, with the 805th Aero Squadron. Its mission was to provide aerial observation support to the Commanding General, Ninth Corps Area. The 805th Observation Squadron was inactivated on 11 June 1937 and then disbanded on 31 May 1942. The Civilian Conservation Corps was organized roughly along army corps area boundaries since most of the logistical administration and support (food, housing, uniforms, transportation) for this 1930s Great Depression-era emergency work program was provided by the U.S. Army. The corps areas provided
Regular Army A regular army is the official army of a state or country (the official armed forces), contrasting with irregular forces, such as volunteer irregular militias, private armies, mercenaries, etc. A regular army usually has the following: * a standi ...
officers to oversee these tasks. In time, they were replaced by officers of the Organized Reserve, freeing Regular Army officers to return to their assigned duties and providing practical experience to the Reserve officers.


The end of the "corps area" concept

General
Douglas MacArthur Douglas MacArthur (26 January 18805 April 1964) was an American military leader who served as General of the Army for the United States, as well as a field marshal to the Philippine Army. He had served with distinction in World War I, was ...
, the Army's Chief of Staff, believed that the 1921 mobilization plan was based on unsound assumptions and that the Army required active field army headquarters before the start of any mobilization to manage the integration and training of subordinate units as they mobilized. He also concluded that the existing three army area/six army arrangement was too ponderous to field a force that might be needed in a hurry and that existing mobilization plans were not flexible enough to tailor to various war plans then in existence. After a War Department study, MacArthur on 9 August 1932 constituted three new army headquarters in the Regular Army (the headquarters of the
First United States Army First Army is the oldest and longest-established field army of the United States Army. It served as a theater army, having seen service in both World War I and World War II, and supplied the US army with soldiers and equipment during the Kor ...
was already constituted) and outlined the organization of what became known as the "four army" plan, which effectively abolished the three army area/six army system. On 3 October 1940, the War Department transferred tactical command functions to General Headquarters, U.S. Army, separating the field armies from the corps areas. Corps areas were then limited to their Zone of the Interior functions as ''service commands'' and the field armies assumed control of all tactical units. In 1942, after the start of World War II and by executive order, the army level organizations took to training or the field as home defense and combat commands under the control of
Army Ground Forces The Army Ground Forces were one of the three autonomous components of the Army of the United States during World War II, the others being the Army Air Forces and Army Service Forces. Throughout their existence, Army Ground Forces were the larg ...
. In March 1942, home defense and training activities were assigned to the newly formed
Eastern Eastern may refer to: Transportation *China Eastern Airlines, a current Chinese airline based in Shanghai * Eastern Air, former name of Zambia Skyways *Eastern Air Lines, a defunct American airline that operated from 1926 to 1991 * Eastern Air ...
, Central, Southern, and
Western Western may refer to: Places *Western, Nebraska, a village in the US *Western, New York, a town in the US *Western Creek, Tasmania, a locality in Australia *Western Junction, Tasmania, a locality in Australia *Western world, countries that id ...
Defense Commands, which overlaid the existing Corps Areas. The geographical corps areas were redesigned as numbered service commands under the
Services of Supply The Services of Supply or "SOS" branch of the Army of the USA was created on 28 February 1942 by Executive Order Number 9082 "Reorganizing the Army and the War Department" and War Department Circular No. 59, dated 2 March 1942. Services of Supp ...
on 22 July 1942 (renamed in 1943 as
Army Service Forces The Army Service Forces was one of the three autonomous components of the United States Army during World War II, the others being the Army Air Forces and Army Ground Forces, created on 9 March 1942. By dividing the Army into three large command ...
, the ASF). They served the Army's supply system, and performed administration, and "housekeeping" functions within the United States such as the issuance of Army serial numbers and the operation of induction centers and army posts located in the United States and its territories. By this time, the corps area boundaries and departments experienced some minor readjustments: *
Eastern Defense Command The Eastern Defense Command was first established as the Northeast Defense Command on 17 March 1941 as one of four U.S. Army continental defense commands to plan and prepare for and execute defense against enemy attack in the months before Americ ...
(co-headquartered with First Army until October 1943) **1st Corps Area – ME, VT, NH, MA, CT, RI **2nd Corps Area – NY, NJ, DE **3rd Corps Area – PA, MD, VA, DC **4th Corps Area – NC, SC, GA, FL, AL, MS, TN * Central Defense Command (co-headquartered with Second Army) **5th Corps Area – OH, IN, KY, WV **6th Corps Area – IL, MI, WI **7th Corps Area – MO, KS, NE, CO, IA, MN, ND, SD, WY * Southern Defense Command (co-headquartered with Third Army until December 1943) **8th Corps Area – AR, LA, TX, OK, NM *
Western Defense Command Western Defense Command (WDC) was established on 17 March 1941 as the command formation of the United States Army responsible for coordinating the defense of the Pacific Coast region of the United States during World War II. A second major resp ...
(co-headquartered with Fourth Army) **9th Corps Area – WA, OR, CA, ID, MT, NV, UT, AK *
Hawaiian Department Hawaiian may refer to: * Native Hawaiians, the current term for the indigenous people of the Hawaiian Islands or their descendants * Hawaii state residents, regardless of ancestry (only used outside of Hawaii) * Hawaiian language Historic uses * ...
*
Panama Canal Department The Panama Canal Department was a department (geographical command) of the United States Army, responsible for the defense of the Panama Canal Zone between 1917 and 1947. First U.S. Army presence The Isthmian Canal Commission and the Panama Ca ...
*
Philippine Department The Philippine Department (Filipino: ''Kagawaran ng Pilipinas/Hukbong Kagawaran ng Pilipinas'') was a regular United States Army organization whose mission was to defend the Philippine Islands and train the Philippine Army. On 9 April 1942, durin ...
* Puerto Rican Department


Abolition of the Service Commands

On 30 August 1945, Army Chief of Staff General
George Marshall George Catlett Marshall Jr. (December 31, 1880 – October 16, 1959) was an American army officer and statesman. He rose through the United States Army to become Chief of Staff of the US Army under Presidents Franklin D. Roosevelt and Harry S ...
created a board headed by Lieutenant General
Alexander M. Patch General Alexander McCarrell Patch (November 23, 1889 – November 21, 1945) was a senior United States Army officer who fought in both world wars, rising to rank of general. During World War II, he commanded U.S. Army and Marine Corps force ...
to review the organization of the War Department. The board had no officers from the ASF staff but two came from the technical services. The board submitted its recommendations to the Chief of Staff on 18 October. These were that the technical services be continued, with the Transportation Corps made permanent, and that the Finance Department becoming an eighth technical service. The service commands would be abolished, and their functions transferred to the Armies. The ASF would also be abolished, and its staff sections transferred to the War Department General Staff. In accordance with these recommendations, on 11 June 1946, Army Service Forces and the nine service commands areas were abolished. The service commands were replaced by six field army level organizations. These six Army Areas, though similar in name, operated on a functional rather than geographic basis but roughly followed along the old corps areas boundaries. * First Army Area, headquartered at
Fort Jay Fort Jay is a coastal bastion fort and the name of a former United States Army post on Governors Island in New York Harbor, within New York City. Fort Jay is the oldest existing defensive structure on the island, and was named for John Jay, a mem ...
in New York, New York included ME, NH, VT, MA, RI, CT, NJ, NY and DE. * Second Army Area, headquartered at Baltimore, Maryland included PA, MD, VA, WV, OH, IN and KY. * Third Army Area, headquartered variously in rented office space in downtown Atlanta and in 1946 at
Fort McPherson Fort McPherson was a U.S. Army military base located in Atlanta, Georgia, bordering the northern edge of the city of East Point, Georgia. It was the headquarters for the U.S. Army Installation Management Command, Southeast Region; the U.S. A ...
in Atlanta, Georgia included NC, SC, GA, FL, AL, TN and MS * Fourth Army Area, headquartered at
Fort Sam Houston Fort Sam Houston is a U.S. Army post in San Antonio, Texas. "Fort Sam Houston, TX • About Fort Sam Houston" (overview), US Army, 2007, webpageSH-Army. Known colloquially as "Fort Sam," it is named for the U.S. Senator from Texas, U.S. Represen ...
in San Antonio, Texas included TX, AR, LA, OK, and NM. * Fifth Army Area, headquartered at Fort Sheridan near Chicago, Illinois included IL, MI, WI, MN, IA, MO, KS, NE, ND, SD, WY and CO. * Sixth Army Area, headquartered at
Presidio of San Francisco The Presidio of San Francisco (originally, El Presidio Real de San Francisco or The Royal Fortress of Saint Francis) is a park and former U.S. Army post on the northern tip of the San Francisco Peninsula in San Francisco, California, and is part o ...
, California included WA, OR, ID, MT, UT, NV and CA. The postwar
Seventh United States Army The Seventh Army was a United States army created during World War II that evolved into the United States Army Europe (USAREUR) during the 1950s and 1960s. It served in North Africa and Italy in the Mediterranean Theater of Operations and Fra ...
in Germany and
Eighth United States Army The Eighth Army is a U.S. field army which is the commanding formation of all United States Army forces in South Korea. It commands U.S. and South Korean units and is headquartered at the Camp Humphreys,Training and Doctrine Command The United States Army Training and Doctrine Command (TRADOC) is a major command of the United States Army headquartered at Fort Eustis, Virginia. It is charged with overseeing training of Army forces and the development of operational doctrine. ...
.


See also

*
Structure of the United States Army The structure of the United States Army is complex, and can be interpreted in several different ways: active/reserve, operational/administrative, and branches/functional areas. From time to time the Department of the Army issues Department of ...
*
History of the United States Army The history of the United States Army began in 1775. From its formation, the United States Army has been the primary land based part of the United States Armed Forces. The Army's main responsibility has been in fighting land battles and military ...


Notes


References

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Further reading

* {{Cite book , last1=Conn , first1=Stetson , last2=Engelman, first2=Rose C., last3=Fairchild, first3=Byron, title=Guarding the United States and its Outposts, url=http://www.history.army.mil/books/wwii/Guard-US/index.htm#contents, series=United States Army in World War II, orig-year=1964, year=2000, publisher =Center of Military History, United States Army, location=Washington, D.C. Military units and formations disestablished in 1940